A couple of our servers have ST32000641AS (2TB Seagate desktop drives) in RAID 10 using an Adaptec 2405 controller. I've been told by Adaptec that this is a bad idea and we have, in fact, already seen one raid system go down using these drives. Since this is a 24/7 system, my question is whether it would be possible to switch over to WD RE4 2TB raid edition drives (model WD2003FYYS) by hot swapping them, one by one until we've migrated over. We would wait between each drive to make sure the raid has rebuilt itself.

In theory, this should work... however, one thing I can't figure out is whether these drives are the exact same size or not. Unfortunately, the raid build on the ST32000641AS drives are partitioned to capacity. If the WD2003FYYS drives are even the slightest bit smaller, it's not going to work. Any ideas on where I can go to learn whether the WD2003FYYS drive is exactly as big (or bigger) than then ST32000641AS?

One of the problems using desktop drives is with TLER. By swapping out the drives one at a time, you may end up exacerbating the problem on the remaining three drives. Do make sure you have multiple, current, tested backups. We have had a similar situation and ended up creating a parallel RAID 10 system with the RE4 level drives instead.
–
tegbainsAug 21 '12 at 6:51

2

Thanks for all the comments. For the record, it was our server vendor who sold us the server with desktop drives in it. They claim to have sold "hundreds" of raid systems using desktop drives, with "no problems". However, we've learned the hard way that it is definitely a bad idea because, as @tegbains has noted, desktop drives lack TLER and the controller dropped two drives at the same time and the server crashed. Neither drive tested as "bad"... just a lot of "aborted commands".
–
CurtisAug 21 '12 at 15:06

Thanks, @CristianCiupitu! This is exactly what I was looking for. I guess I should have thought to check the manual. I guess I didn't expect the manual to provide the specs in such great detail.
–
CurtisAug 21 '12 at 15:10